Research and analysis

Sickle cell and thalassaemia screening: data report 2018 to 2019

Published 29 March 2021

Applies to England

© Crown copyright 2021

This publication is licensed under the terms of the Open Government Licence v3.0 except where otherwise stated. To view this licence, visit nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: psi@nationalarchives.gov.uk.

Where we have identified any third party copyright information you will need to obtain permission from the copyright holders concerned.

This publication is available at https://www.gov.uk/government/publications/sickle-cell-and-thalassaemia-screening-data-report-2018-to-2019/sickle-cell-and-thalassaemia-screening-data-report-2018-to-2019

In this report we use ‘screening year 2018 to 2019’ to refer to 1 April 2018 to 31 March 2019.

For an overview of national screening figures, please see table A of the accompanying additional information spreadsheet. Details about these overview figures are included in this report.

1. Executive summary

This report presents screening data for the NHS sickle cell and thalassaemia (SCT) screening programme for the screening year 2018 to 2019.

The report contains data submitted by antenatal screening laboratories, prenatal diagnostic (PND) laboratories, newborn screening laboratories and newborn DNA testing laboratories. Detailed presentation of screening standards data is not included in this report, as this is contained within the annual antenatal standards data report.

In screening year 2018 to 2019, the NHS screened around 670,000 pregnant women for sickle cell, thalassaemia and other haemoglobin variants. It also screened around 626,000 newborn babies for sickle cell disease (SCD).

The proportion of pregnant women in England with screen positive results remained stable in screening year 2018 to 2019 compared with previous years. In women with a screen positive result, the most common identified risk to pregnancy was a baby born with a possible sickle cell condition (51% of women with a screen positive result), followed by a baby born with a possible beta thalassaemia condition (34% of women with a screen positive result).

There were 341 prenatal diagnostic (PND) tests performed in screening year 2018 to 2019, a decrease compared with previous years. The proportion of PND tests performed at less than or equal to 12+6 weeks gestation increased slightly in screening year 2018 to 2019 but remained lower than between screening years 2008 to 2009 and 2013 to 2014.

In England in screening year 2018 to 2019, approximately 1 in 2,100 babies screened for SCD were positive for significant conditions, and 1 in 79 were carriers of SCD. The rates of babies screening positive for a significant condition increased slightly in screening year 2018 to 2019 compared with the previous year, both in London and the rest of England. There was no corresponding increase in rates of babies identified with carrier results.

There is a continuing trend of increases in the rate of declines for newborn screening for SCD, with the rate in screening year 2018 to 2019 being 5.23 per 1,000 babies screened. We identified where increases in declines were seen; most declines were in older babies, and those offered screening by health visitors rather than midwifery units, usually babies that move into the area.

2. Methodology

The NHS SCT screening programme has 9 screening standards. Screening standards provide reliable and timely information about the quality of the screening programme, across the whole screening pathway. The SCT screening standards are presented in the annual antenatal standards reports.

In addition to the SCT screening standards, some standards within the NHS newborn blood spot (NBS) screening programme are also relevant to the NHS SCT screening programme. These include standards relating to coverage and blood spot test processes, such as timely sample collection. The NBS screening standards are presented in annual reports. For standards that are also key performance indicators (KPIs), data are presented in the KPI reports.

As the screening standards are presented in the above reports, this report presents data that is additional to the screening standards. The collection of this data is described below.

Timely annual data returns are required from all antenatal and newborn screening laboratories in line with laboratory guidance and Service Specification no.18: NHS Sickle Cell and Thalassaemia Screening Programme. Data is collected using spreadsheet-based data templates. The data is checked on receipt and, if required, the relevant laboratory is contacted for any clarifications that are needed.

While the screening programme covers only England, screening data is provided by the newborn laboratories in Scotland, Wales and Northern Ireland. However, these countries are not included in the ethnicity figures, as Scotland uses different ethnic categories, and Wales and Northern Ireland do not routinely collect ethnicity data.

The National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) provides a de-personalised dataset of PND test data to the programme. This data is collected from PND laboratories and verified by NCARDRS.

The 2 newborn DNA testing laboratories in England also submit aggregated data to the programme annually.

3. Antenatal screening

3.1 Antenatal screening laboratory data quality and completeness

Out of 145 expected antenatal screening laboratory returns, there were 138 received for screening year 2018 to 2019 (95.2% response rate). The expected data returns are based on the maternity providers served by the screening laboratory, and one screening laboratory may serve more than one maternity provider.

Not all laboratories were able to submit data for all requested fields. Data fields were excluded where providers were unable to submit data. Where exclusions were made, these are identified below the relevant charts and tables. Some laboratories are unable to match the mother results to biological father results and so cannot provide the number of couples where pregnancy is at risk of a clinically significant disorder, requiring referral for counselling. As a result, the reported number is likely to be an under-estimate of the true number of couples where pregnancy is at risk of a clinically significant disorder.

3.2 Numbers screened and detected in antenatal screening

In screening year 2018 to 2019, after data exclusions were applied, there were 660,070 antenatal care bookings reported in the included returns, of which 13,296 were identified as screen positive (approximately 1 in 50 women screened). Of these women with screen positive results, 831 pregnancies were identified as being at risk of the baby inheriting a clinically significant sickle cell or thalassaemia condition (approximately 1 in 16 women with screen positive results) based on the results of both parents.

These pregnancies are those represented by the orange boxes in the SCT antenatal return form, and include all pregnancies where there is a 1 in 4 chance or higher of the fetus having a clinically significant haemoglobin disorder. While referral for counselling is required for all of these pregnancies, PND must be offered for the serious conditions, as described in the inheritance risk table within the sickle cell and thalassaemia screening handbook. Please note that in previous editions of this report the ‘at risk’ couples were the pregnancies at risk of the more serious haemoglobin disorders only.

Table 1: Numbers screened and detected, England, screening year 2018 to 2019

Region (returns included/expected)† Antenatal screening samples (n) Screen positive (n) Screen positive (% of samples) Pregnancy at risk of clinically significant disorder (n) Pregnancy at risk of clinically significant disorder (% of Scr+)
London (24/26) 136,354 5,764 4.23 374 6.49
Midlands and East (40/41) 202,629 3,649 1.80 229 6.28
North (37/41) 176,516 2,295 1.30 132 5.75
South (35/37) 144,571 1,588 1.10 96 6.05
England (136/145) 660,070 13,296 2.01 831 6.25

†Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of pregnancies at risk of a clinically significant disorder were all accepted.

Table 2: Numbers screened and detected, high prevalence areas, England, screening year 2018 to 2019

Region (returns included/expected)† Antenatal screening samples (n) Screen positive (n) Screen positive (% of samples) Pregnancy at risk of clinically significant disorder (n) Pregnancy at risk of clinically significant disorder (% of Scr+)
London (24/26) 136,354 5,764 4.23 374 6.49
Midlands and East (18/18) 111,166 2,873 2.58 190 6.61
North (11/13) 81,236 1,712 2.11 112 6.54
South (9/9) 47,383 803 1.69 68 8.47
England (62/66) 376,139 11,152 2.96 744 6.67

† Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of pregnancies at risk of a clinically significant disorder were all accepted.

Table 3: Numbers screened and detected, low prevalence areas, England, screening year 2018 to 2019

Region (returns included/expected)† Antenatal screening samples (n) Screen positive (n) Screen positive (% of samples) Pregnancy at risk of a clinically significant disorder (n) Pregnancy at risk of a clinically significant disorder (% of Scr+)
London (0/0) - - - - -
Midlands and East (22/23) 91,463 776 0.85 39 5.03
North (26/28) 95,280 583 0.61 20 3.43
South (26/28) 97,188 785 0.81 28 3.57
England (74/79) 283,931 2,144 0.76 87 4.06

† Expected returns are not included when no data return was received or when exclusions to received data have been made. Received data returns are only included above if data for number of samples, number of screen positives and number of pregnancies at risk of a clinically significant disorder were all accepted.

Figure 1: Screen positive women as a percentage of antenatal screening samples received by laboratory, England, 2018 to 2019

London had a higher percentage of screen positive women than the rest of England from screening year ending 2011 to that ending 2019.

In London, the percentage of antenatal screening samples that were screen positive decreased in screening year 2018 to 2019 following a small increased in screening year 2017 to 2018 (Figure 1). In the rest of England, the percentage of screen positives has remained stable since screening year 2010 to 2011.

Some returns are not included as data was not received or excluded for screening years:

  • 2010 to 2011 (3 returns)
  • 2011 to 2012 (2 returns)
  • 2012 to 2013 (3 returns)
  • 2013 to 2014 (2 returns)
  • 2014 to 2015 (4 returns)
  • 2015 to 2016 (6 returns)
  • 2016 to 2017 (10 returns)
  • 2017 to 2018 (14 returns)
  • 2018 to 2019 (8 returns)

3.3 Declined antenatal screening tests for SCT

Personal informed choice is an important element of population screening, and as such, screening tests for SCT may be declined for various reasons. Table 4 shows, after data exclusions, the number of declines of antenatal screening reported by screening laboratories, as a proportion of total booking blood samples tested.

While antenatal screening laboratories have reported the data shown in table 4, the number of declines is also reported by maternity services in data returns for the coverage standard, SCT-S01. Differences between declines reported by laboratories and maternity providers have been noted, and the programme will continue work to investigate this further and determine how declines will be published in future.

Table 4: Declined antenatal screening by region, England, screening years ending 2017 to that ending 2019

Screening year 2016 to 2017

Region Antenatal screening samples Declines % of samples
London 102,338 37 0.04
Midlands and East 204,425 384 0.19
North 171,791 1,029 0.60
South 144,806 857 0.59
England 623,360 2,307 0.37

Returns not included as data not received or excluded: 8.

Screening year 2017 to 2018

Region Antenatal screening samples Declines % of samples
London 82,840 44 0.05
Midlands and East 191,000 252 0.13
North 162,541 571 0.35
South 134,773 249 0.18
England 571,154 1,116 0.20

Returns not included as data not received or excluded: 29.

Screening year 2018 to 2019

Region Antenatal screening samples Declines % of samples
London 117,278 37 0.03
Midlands and East 184,896 175 0.09
North 171,495 242 0.14
South 133,167 237 0.18
England 606,836 691 0.11

Returns not included as data not received or excluded: 19.

Figure 2 shows the trends in rates of declines for antenatal screening since screening year 2007 to 2008, broken down by high and low prevalence areas. Reported rates of declines have decreased over time, and in screening year 2018 to 2019 were at the lowest level since reporting began in screening year 2007 to 2008. Since screening year 2017 to 2018, rates of declines have been similar across high and low prevalence areas, following a period in which decline rates were consistently higher in low prevalence areas.

Some returns are not included as data was not received or excluded for screening years:

  • 2007 to 2008 (40 returns)
  • 2008 to 2009 (46 returns)
  • 2009 to 2010 (42 returns)
  • 2010 to 2011 (18 returns)
  • 2011 to 2012 (15 returns)
  • 2012 to 2013 (16 returns)
  • 2013 to 2014 (15 returns)
  • 2014 to 2015 (15 returns)
  • 2015 to 2016 (13 returns)
  • 2016 to 2017 (18 returns)
  • 2017 to 2018 (29 returns)
  • 2018 to 2019 (19 returns)

3.4 Testing of the baby’s biological father

If a woman has a screen positive result, the baby’s biological father should be offered testing to determine the risk to the pregnancy. If the baby’s biological father is not available for testing, it is more difficult to accurately assess the baby’s risk of inheriting SCT. In this situation, women are counselled and offered PND. It is estimated this group of women accounts for approximately 31% of screen positive women (calculated from the number of women with a screen positive result minus the number of biological father results available).

Uptake of biological father testing is higher in low prevalence areas compared to high prevalence areas. Uptake of biological father testing has increased in high prevalence areas since screening year 2010 to 2011 and is now at about 65%. Uptake of biological father testing has been variable in low prevalence areas since recording began in screening year 2008 to 2009 but is now at 80%. The biggest increases in uptake have occurred in high prevalence areas. Uptake of testing of the baby’s biological father increased slightly in screening year 2018 to 2019.

Some returns are not included as data was not received or excluded for screening years:

  • 2007 to 2008 (23 returns)
  • 2008 to 2009 (15 returns)
  • 2009 to 2010 (22 returns)
  • 2010 to 2011 (7 returns)
  • 2011 to 2012 (9 returns)
  • 2012 to 2013 (10 returns)
  • 2013 to 2014 (11 returns)
  • 2014 to 2015 (11 returns)
  • 2015 to 2016 (7 returns)
  • 2016 to 2017 (11 returns)
  • 2017 to 2018 (18 returns)
  • 2018 to 2019 (9 returns)

Percentage uptake will include father results known from historical records in line with guidance in the handbook for laboratories.

Table 5: Uptake of testing of the baby’s biological father, England, screening year ending 2017 to that ending 2019

Screening year 2016 to 2017

Region Father samples requested Father results available % uptake
London 5,291 3,044 57.5
Midlands and East 3,747 2,494 66.6
North 2,352 1,623 69.0
South 1,866 1,352 72.5
England 13,256 8,513 64.2

Returns not included as data not received or excluded: 11.

Screening year 2017 to 2018

Region Father samples requested Father results available % uptake
London 5,361 2,947 55.0
Midlands and East 3,580 2,449 68.4
North 2,375 1,681 70.8
South 1,823 1,367 75.0
England 13,139 8,444 64.3

Returns not included as data not received or excluded: 18.

Screening year 2018 to 2019

Region Father samples requested Father results available % uptake
London 6,041 3,772 62.4
Midlands and East 3,857 2,656 68.9
North 2,484 1,845 74.3
South 1,919 1,587 82.7
England 14,301 9,860 68.9

Returns not included as data not received or excluded: 9.

Father results available includes results known from historical records in line with guidance in the handbook for laboratories.

3.5 Breakdown of pregnancy risk

For women with a screen positive result, the most common identified risk to the pregnancy was the baby having possible SCD, followed by a baby having possible beta thalassaemia (Figure 4). Figures are rounded and therefore do not appear to equal 100%.

Figure 4: Screen positive women, broken down by risk to the pregnancy, England, screening year 2018 to 2019

Risk to pregnancy Baby with possible sickle cell disease Baby with possible beta thalassaemia Baby with possible alpha thalassaemia Other clinically significant results Other Hb variants requiring testing of baby’s father Total
% 51 34 5 6 3 100

Based on the results of both parents, it can be determined whether the pregnancy is at risk of a haemoglobin disorder. Breakdown data is requested on both biological mother and father results to identify the specific risk of an affected pregnancy. This information also allows us to separate SCT screen positive results and to identify cases where the baby’s biological father was not available for testing or the laboratory is unable to link the results to the mother’s results. Table B in the accompanying additional information spreadsheet shows the breakdown of the pregnancy risk for screen positive women in more detail.

4. Prenatal diagnosis (PND)

Early antenatal screening for SCT is important as this will maximise the opportunity for parents to make a personal informed choice. Where parents choose to have PND, advanced gestational age may limit reproductive choices. Figure 5 demonstrates that the proportion of PND tests performed at less than or equal to 12+6 weeks gestation increased slightly in screening year 2018 to 2019 compared to the previous year but remains lower than in the years up to screening year 2013 to 2014.

Table 6: Gestation at PND test, England, screening year ending 2017 to that ending 2019

Gestation at PND test 2016 to 2017 n (%) 2017 to 2018 n (%) 2018 to 2019 n (%)
≤12+6 weeks 139 (37.2) 152 (41.5) 147 (43.1)
13+0 to 14+6 weeks 110 (29.4) 88 (24.0) 89 (26.1)
≥ 15+0 weeks 122 (32.6) 125 (34.2) 104 (30.5)
Unknown gestation 3 (0.8) 1 (0.3) 1 (0.3)
Total 374 (100.0) 366 (100.0) 341 (100.0)

PND tests for women from devolved nations that were tested at English laboratories have been excluded. Gestation relates to the gestation on the day of fetal sampling.

Figure 5: Proportion of PND tests performed by gestation, England, screening year ending 2009 to that ending 2019

Year Proportion of PNDs performed ≤ 12+6 weeks Proportion of PNDs performed > 12+6 weeks Unknown gestation Total
2008 to 2009 47.2 47.7 5.2 100
2009 to 2010 50.3 47.0 2.8 100
2010 to 2011 48.1 50.7 1.2 100
2011 to 2012 52.4 45.7 1.9 100
2012 to 2013 49.7 48.7 1.5 100
2013 to 2014 51.3 47.9 0.8 100
2014 to 2015 40.0 58.2 1.8 100
2015 to 2016 40.0 59.5 0.5 100
2016 to 2017 37.2 62.0 0.8 100
2017 to 2018 41.5 58.2 0.3 100
2018 to 2019 43.1 56.6 0.3 100

Figures are rounded and therefore do not appear to equal 100%. PND tests for women from devolved nations that were tested at English laboratories have been excluded.

4.1 Numbers tested and detected in prenatal diagnostic testing

There are 4 laboratories in England that undertake genetic analysis of the PND test. There were 341 PND tests performed in screening year 2018 to 2019, a decrease compared to previous years.

Figure 6: Number of PND tests performed, by laboratory, England, screening year ending 2009 to that ending 2019

Year KCH Manchester Oxford UCLH Total
2008 to 2009 101 0 166 119 386
2009 to 2010 119 0 159 118 396
2010 to 2011 141 0 159 120 420
2011 to 2012 134 0 149 135 418
2012 to 2013 125 0 161 112 398
2013 to 2014 104 31 140 109 384
2014 to 2015 138 25 139 131 433
2015 to 2016 120 34 130 123 407
2016 to 2017 113 28 116 117 374
2017 to 2018 109 29 102 126 366
2018 to 2019 90 34 110 107 341

PND tests for women from devolved nations that were tested at English laboratories have been excluded.

Breakdown of PND results

Table 7: Breakdown of PND fetal results by condition, England, screening year ending 2017 to that ending 2019

Where PND fetal result is a haemoglobinopathy

PND result 2016 to 2017 2017 to 2018 2018 to 2019
HbSS 55 55 46
HbSC 8 12 7
HbS/beta thalassaemia 2 4 5
HbS+other 0 2 0
Alpha thalassaemia 3 0 2
Beta thalassaemia 10 19 12
Other 2 0 2

Where PND fetal result is a carrier

PND result 2016 to 2017 2017 to 2018 2018 to 2019
Hb AS 146 130 112
Hb AC 3 13 10
Alpha thalassaemia carrier 2 6 2
Beta thalassaemia carrier 36 32 27
Other Hb carrier 3 3 2

Where PND fetal result is no abnormality detected

PND risk 2016 to 2017 2017 to 2018 2018 to 2019
Risk for sickle cell 77 65 86
Risk for thalassaemia 20 12 17
Risk for sickle cell / Beta thalassaemia 7 12 17
Risk not known 0 1 3

PND tests for women from devolved nations that were tested at English laboratories have been excluded. ‘Other’ includes other haemoglobinopathy variants; ‘Risk not known’ includes cases where no data was provided by the PND laboratory.

4.2 Prenatal diagnostic tests by family origin

Table 8: Number of PND tests by mother’s family origins, England, screening year ending 2017 to that ending 2019

Mother’s family origin 2016 to 2017 2017 to 2018 2018 to 2019
  n (%) n (%) n (%)
African/African-Caribbean 273 (73.0) 254 (69.4) 228 (66.9)
South Asian 33 (8.8) 26 (7.1) 25 (7.3)
South East Asian/Other Asian 9 (2.4) 9 (2.5) 10 (2.9)
Other Non-European 14 (3.7) 10 (2.7) 9 (2.6)
Southern and other European 16 (4.3) 14 (3.8) 20 (5.9)
Mixed 5 (1.3) 7 (1.9) 8 (2.3)
Northern European/United Kingdom (White) 1 (0.3) 3 (0.8) 1 (0.3)
Not known 23 (6.1) 43 (11.7) 40 (11.7)
Total 374 (100.0) 366 (100.0) 341 (100.0)

PND tests for women from devolved nations that were tested at English laboratories have been excluded. Mother’s family origin is recorded in data received from PND laboratories. Categories have then been assigned to mother’s family origin based upon the categories used in the family origin questionnaire (FOQ).

The data received from PND laboratories do not currently always allow African and African-Caribbean family origins to be accurately separated. The programme has taken steps to rectify this, so in future African and African-Caribbean family origins can be reported separately.

4.3 Pregnancy outcomes

One of the aims of the NHS SCT screening programme is to ensure personal informed choice. The screening programme collects data on pregnancy outcomes following PND testing to assess what choices women and couples make following the test. There are gaps in the data, with the pregnancy outcome not known for 15% of affected pregnancies in the screening year 2018 to 2019 dataset. This is an improvement in data completeness compared to previous years.

Table 9: Outcomes for pregnancies with haemoglobinopathy fetal results at PND, England, screening year ending 2017 to that ending 2019

Sickle cell

Pregnancy outcome 2016 to 2017 % of total identified with condition 2017 to 2018 % of total identified with condition 2018 to 2019 % of total identified with condition
Continued 33.9 32.4 37.5
Terminated 43.6 36.6 46.4
Not known 22.6 31.0 16.1

Beta thalassaemia

Pregnancy outcome 2016 to 2017 % of total identified with condition 2017 to 2018 % of total identified with condition 2018 to 2019 % of total identified with condition
Continued 20.0 31.6 23.1
Terminated 70.0 57.9 61.5
Not known 10.0 10.5 15.4

Alpha thalassaemia

Pregnancy outcome 2016 to 2017 % of total identified with condition 2017 to 2018 % of total identified with condition 2018 to 2019 % of total identified with condition
Continued 0.0 - 0.0
Terminated 100.0 - 100.0
Not known 0.0 - 0.0

The ‘sickle cell’ category includes:

  • person with sickle haemoglobin (HbSS)
  • person with sickle and C variant haemoglobins (HbSC)
  • person with sickle haemoglobin and beta thalassaemia (HbS/beta thalassaemia)
  • person with sickle and other variant haemoglobins (HbS+other variant) requiring clinical follow-up

Other haemoglobin variants are not presented, and miscarriage outcomes have been excluded. Please note that alpha thalassaemia percentages are based on small numbers and should be interpreted with caution.

Figure 7: Outcomes for pregnancies with haemoglobinopathy diagnosis at PND, England, screening year ending 2009 to that ending 2019

Haemoglobinopathy diagnosis Terminated (%) Continued (%) Outcome not known (%) Total
Sickle cell† 41.9 26.0 32.1 100
Beta thalassaemia 52.3 15.0 32.6 100
Alpha thalassaemia 73.1 7.7 19.2 100

† The ‘sickle cell’ category includes HbSS, HbSC, HbS/beta thalassaemia, and HbS+other variant requiring clinical follow-up.

Excludes miscarriage outcomes due to small numbers.

Figure 8: Outcomes for pregnancies with haemoglobinopathy diagnosis at PND (known outcomes only), England, screening year ending 2009 to that ending 2019

Haemoglobinopathy diagnosis Terminated (%) Continued (%) Total
Sickle cell† 61.7 38.3 100
Beta thalassaemia 77.7 22.3 100
Alpha thalassaemia 90.5 9.5 100

† The ‘sickle cell’ category includes HbSS, HbSC, HbS/beta thalassaemia, and HbS+other variant requiring clinical follow-up.

Excludes miscarriage outcomes and 330 cases where pregnancy outcome was not known.

Figure 9: Outcomes for pregnancies with haemoglobinopathy diagnosis at PND, by gestation at PND (known outcomes only), England, screening year ending 2009 to that ending 2019

Gestation Terminated (%) Continued (%) Total
≤ 12+6 weeks 76.4 23.6 100
13+0 to 14+6 weeks 66.9 33.1 100
≥ 15+0 weeks 47.3 52.7 100

Excludes unknown and miscarriage outcomes, and cases where the gestation at PND was unknown.

5. Newborn screening for SCD

Numbers screened and results

Screen positive results for significant conditions comprise:

  • baby with fetal and sickle haemoglobins (FS)
  • baby with fetal, sickle and C variant haemoglobins (FSC)
  • baby with fetal, sickle and other variant haemoglobins (FS-other)
  • baby with fetal and E variant haemoglobins (FE)

These results indicate the condition is suspected, with further confirmatory testing required to confirm diagnosis.

Carrier results comprise:

  • baby with fetal, adult and sickle haemoglobins (FAS)
  • baby with fetal, adult and C variant haemoglobins (FAC)
  • baby with fetal, adult and D variant haemoglobins (FAD)
  • baby with fetal, adult and E variant haemoglobins (FAE)
  • other haemoglobin variants

Table 10: Numbers and rates of significant condition and carrier screening results, NBS screening for sickle cell disease, United Kingdom, screening year 2018 to 2019

Significant conditions

Region Babies tested n Rate / 1000 1 in x
London 123,121 143 1.16 861
Midlands and East 185,215 67 0.36 2,764
North 165,264 47 0.28 3,516
South 142,859 25 0.17 5,714
Unknown region 10,196 8 0.78 1,275
England total 626,655 290 0.46 2,161
Scotland 51,618 5 0.10 10,324
Wales † 31,048 3 0.10 10,349
Northern Ireland 22,849 1 0.04 22,849
UK total 732,170 299 0.41 2,449

Carriers

Region Babies tested n Rate / 1000 1 in x
London 123,121 3,463 28.13 36
Midlands and East 185,215 2,105 11.37 88
North 165,264 1,222 7.39 135
South 142,859 1,008 7.06 142
England total 732,170 8,207 11.21 89
Scotland 51,618 234 4.53 221
Wales † 31,048 - - -
Northern Ireland 22,849 37 1.62 618
UK total 732,170 8,207 11.21 89

English region is based upon the maternity provider, clinical commissioning group (CCG) or child health record department (CHRD) of the baby. The geography used differs according to the submitting laboratory.

Data is based on samples received into newborn screening laboratories in screening year 2018 to 2019, apart from for Wales, where data is based on babies tested from the cohort of eligible babies born in screening year 2018 to 2019.

Babies identified to be from Isle of Man or overseas by newborn screening laboratories have not been included in the above.

† The Wales newborn screening protocol is designed to detect only the disease states of SCD. However, those cases that are identified from the newborn screen process and subsequently determined to be carriers of SCD are referred for follow-up.

For 2 laboratories in England, data provided is based on samples received rather than babies tested.

For a breakdown of newborn screening results, by region, for England in screening yera 2018 to 2019, please see Table C in the accompanying additional information spreadsheet.

Significant conditions comprise FS, FSC, FS Other and FE.

Figure 10 shows the rates of babies screening positive for a significant condition increased slightly in screening year 2018 to 2019 compared with the previous year, both in London and the rest of England. In London, this increase comes after a 3-year period in which rates stabilised, following a period of sustained declines in rates from screening year ending 2008 to that ending 2016.

For the rest of England, this increase means the rate of babies screening positive in screening year 2018 to 2019 was the highest of the period shown in figure 10. There was no corresponding increase in rates of babies identified with carrier results, with rates remaining stable in screening year 2018 to 2019 compared with the previous year, both in London and the rest of England (Figure 11).

Carrier results comprise FAS, FAC, FAD, FAE and other carriers.

The rate of screen positive results for carrier results has steadily decreased in London since reporting began in screening year 2005 to 2006. The rate of screen positive results for carrier results in the rest of England has remained stable since reporting began in screening year 2005 to 2006.

Results by ethnicity

Table 11: Numbers and rates of significant conditions and carrier screening results by ethnic category, screening year 2018 to 2019: English laboratories

Significant conditions

Ethnic category No. of babies tested n Rate/1000 1 in x
White 446,283 5 0.01 89,257
Mixed 40,114 24 0.60 1,671
Asian† 70,173 12 0.17 5,848
Black Caribbean 5,402 25 4.63 216
Black African 21,642 187 8.64 116
Any other Black background 3,741 22 5.88 170
Other† 18,675 6 0.32 3,113
Not stated/not known 21,341 9 0.42 2,371
England total 627,371 290 0.46 2,163

Carrier results

Ethnic category No. of babies tested n Rate/1000 1 in x
White 446,283 718 1.61 622
Mixed 40,114 1,542 38.44 26
Asian† 70,173 1,130 16.10 62
Black Caribbean 5,402 703 130.14 8
Black African 21,642 2,974 137.42 7
Any other Black background 3,741 386 103.18 10
Other† 18,675 216 11.57 86
Not stated/not known 21,341 267 12.51 80
England total 627,371 7,936 12.65 79

The table above includes all babies tested in England laboratories. Therefore, babies from outside England but tested within an English laboratory will be included in the above.

† Asian includes ‘Indian’, ‘Pakistani’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Table 12: Breakdown of screen positive babies by ethnic category, percentage of all babies that screen positive for significant conditions, screening year 2018 to 2019: English laboratories

Ethnic category % of screen positive babies
Black African 64.5
Black Caribbean 8.6
Mixed 8.3
Any other Black background 7.6
Asian† 4.1
Not stated / not known 3.1
Other† 2.1
White 1.7
England total 100.0

Includes all babies tested in English laboratories. Therefore, babies from outside England but tested within an English laboratory will be included in the above.

† Asian includes ‘Indian’, ‘Pakistani’, ‘Bangladeshi’ and ‘Any other Asian background’. ‘Other’ includes ‘Chinese’ and ‘Any other ethnic category’.

Figures are rounded and therefore do not appear to equal 100%.

Declined screening test

There have been year-on-year increases in the rate of declined tests since screening year 2008 to 2009, with the largest increase seen between screening year ending 2018 and that ending 2019 (Figure 12). Due to this significant increase, the SCT programme requested further investigations of the data from the 5 newborn screening laboratories with the largest increase in declines in screening year 2018 to 2019. These investigations showed most of the declines were in older babies, and those offered screening by health visitors rather than midwifery units.

The commissioning of the Healthy Child Programme 0 to 19, which was revised in March 2018, has clarified the roles and responsibilities of health visitors to perform blood spot screening for babies aged under one year that move into the area (‘mover-ins’). It is possible this has also resulted in improved reporting of declines for NBS screening in mover-in babies, as there is increased awareness amongst health visitors of the need to send a completed card (with blood spots section blank) to the screening laboratory for all babies for whom screening was declined.

Figure 12: Declined screening tests for SCD, England, screening year ending 2006 to that ending 2019

Data is not included from:

  • Bristol laboratory for the first half of screening year 2005 to 2006
  • Oxford and Portsmouth laboratories for all of screening year 2006 (Oxford laboratory data starts from 1 July 2006)
  • Sheffield laboratory for screening year 2018 to 2019

There were steady increases in the rate of declines from screening year 2005 to 2006. There were steeper increases from screening years ending 2014 to that ending 2018. The greatest increase was between screening year ending 2018 (2.84 per 1,000 babies offered screening) and that ending 2019 (5.23 per 1,000 babies offered screening).

Figure 13 shows the trends in rates of declined screening tests, by ethnicity, for babies where ethnicity is reported. In screening year 2018 to 2019 the highest decline rates were in the ‘Black Caribbean’ and ‘Other’ ethnic categories. The higher rates of declines in non-White ethnicities may be related to the higher number of declines in babies that are mover-ins.

Although not shown in figure 13, the rates of declined screening tests for babies where ethnicity was not stated or not known has increased from approximately 0.9 per 1,000 babies offered screening in screening year 2005 to 2006, to 94 per 1,000 babies offered screening in screening year 2018 to 2019. This is due to decreases in the number of babies with ethnicity not stated or not known, and increases in the declines recorded for these babies over the same period. This may be due to changes in the recording of both ethnicity and declines. The recording of ethnicity may be more likely to be missing for babies where the test was declined.

Figure 13: Declined screening tests for SCD by ethnic category, England, screening year ending 2006 to that ending 2019

There have been increases in the rate of declines for all ethnic categories since reporting began in screening year 2005 to 2006. The steepest increases have been in the ‘Black Caribbean’ and ‘Other’ ethnic categories and these have the highest rates of declines in screening year 2018 to 2019. The ‘any other Black background’ ethnic category peaked between screening year ending 2016 and that ending 2017 but has dropped slightly in screening years ending 2018 and 2019.

The above includes all babies tested in English laboratories. Therefore, babies from outside England but tested within an English laboratory will be included in the above.

† Other includes the ‘Chinese’ and ‘Any other ethnic category’.

Babies with not stated or not known ethnic category have not been included in the above figure.

Data is not included from:

  • Bristol laboratory for the first half of screening year 2005 to 2006
  • Oxford and Portsmouth laboratories for all of screening year 2005 to 2006 (Oxford data starts from 1 July 2006)
  • Bristol and Sheffield laboratories for all of screening year 2018 to 2019

Post-transfusion testing

Haemoglobin analysis is not suitable for testing samples from transfused babies as transfused red cells can survive up to 120 days in circulation. It is therefore important that pre-transfusion samples are taken in line with NBS sampling guidelines. The NHS NBS screening programme introduced a pre-transfusion sample policy in 2008, as detailed in the guidelines for newborn blood spot sampling, which requires that blood spots should be taken for SCD screening before blood transfusion. Figure 14 demonstrates that the incidence of post-transfusion samples has decreased since this policy was introduced, and the rates in England have remained stable over the last 3 years.

Table 13: Number and rates of post-transfusion samples reported by newborn screening laboratories, England, screening year ending 2017 to that ending 2019

Screening year 2016 to 2017

Region n Total tested Rate / 1000
London 205 132,619 1.55
Midlands and East 256 193,207 1.33
North 223 150,425 1.48
South 127 151,437 0.84
Unknown 93 10,701 8.69
England 904 638,389 1.42

Screening year 2017 to 2018

Region n Total tested Rate / 1000
London 190 129,967 1,46
Midlands and East 267 191,340 1.40
North 304 169,140 1.80
South 94 146,255 0.64
Unknown 96 14,084 6.82
England 951 650,786 1.46

Screening year 2018 to 2019

Region n Total tested Rate / 1000
London 165 123,121 1.34
Midlands and East 230 185,215 1.24
North 286 165,264 1.73
South 127 142,859 0.89
Unknown 71 10,196 6.96
England 879 626,655 1.40

Figure 14: Rates of post-transfusion samples, England, screening year ending 2006 to that ending 2019

There was a sharp decrease in the rate of post-transfusion samples between screening year ending 2006 and that ending 2011. Since screening year 2011 to 2012, rates of post-transfusion samples have remained stable.

Data is not included from:

  • Bristol laboratory for the first half of screening year 2005 to 2006
  • Oxford and Portsmouth laboratories not all of screening year 2005 to 2006 (Oxford data starts from 1 July 2006)
  • Manchester laboratory for screening year 2009 to 2010
  • Great Ormond Street Hospital for screening year 2013 to 2014
  • Liverpool laboratory for screening year 2016 to 2017
  • South East Thames laboratory for screening year 2013 to 2014 (excluded for data quality reasons)

The pre-transfusion policy was implemented in screening year 2008 to 2009.

According to the guidelines for newborn blood spot sampling, where it is not possible to take a pre-transfusion sample, DNA testing is required to mitigate the risk of a missed baby. DNA testing is provided by laboratories at King’s College Hospital and Sheffield Children’s Hospital, and the figures from these laboratories are shown in tables 15 and 16.

Table 14: Numbers detected through DNA testing, reported by newborn DNA testing laboratories, England, screening year ending 2015 to that ending 2019

DNA testing 2014 to 2015 2015 to 2016 2016 to 2017 2017 to 2018 2018 to 2019
Total specimens received per year 1,123 1,198 1,071 1,012 1,004
Number of negative results (Hb S not detected) 1,106 1,183 1,054 992 979
Number of heterozygotes 16 15 17 19 21
Number of homozygotes 1 0 0 0 2

Table 15: Number of samples for DNA testing received from each screening laboratory, England, screening year 2018 to 2019

DNA testing laboratory/newborn laboratory Number of samples
King’s College Hospital/Bristol 36
King’s College Hospital/Cambridge 21
King’s College Hospital/Great Ormond Street 125
King’s College Hospital/Oxford 24
King’s College Hospital/Portsmouth 68
King’s College Hospital/South East Thames 163
King’s College Hospital/South West Thames 46
Sheffield/Leeds 76
Sheffield/Liverpool 61
Sheffield/Manchester 75
Sheffield/Newcastle 47
Sheffield/Sheffield 154
Sheffield/West Midlands 108
England total 1,004

6. SCT antenatal data return form

Antenatal data return form part 2: breakdown of screen positive women

A matrix grid used to determine pregnancies at risk of a clinically significant disorder. The mother’s antenatal results are matched to the father’s antenatal result and inputted into the grid. Pregnancies that are at risk of a clinically significant haemoglobin disorder are those identified as having a 1 in 4 chance or higher of the fetus having a clinically significant haemoglobin disorder.

The matrix was changed for the screening year 2018 to 2019 return form to include orange (for pregnancies at risk of a clinically significant disorder – PND should be offered) or white (minimal risk of a clinically significant disorder). The blue boxes indicate the biological father is not a carrier. The yellow boxes indicate the biological father was unavailable for testing or declined testing. The current return form is available on GOV.UK.

Back to top